The increase in sensitivity of photographic light-sensitive materials is of key importance to manufacturers of photographic emulsions.
Various additives are commonly used for increasing the sensitivity of a silver halide photographic emulsion. These additives mainly comprise synthetic polymers and saccharides. Typical examples of these synthetic polymers include the polyacrylamides disclosed in U.S. Pat. Nos. 3,271,158 and 3,514,289. Also, typical examples of the saccharide include dextran as disclosed in U.S. Pat. No. 3,063,838, 3,272,631, etc.
However, when these additives are used in an amount sufficient to achieve their intended purpose, the photographic emulsion layer(s) tend to peel off from the subbing layer. Subbing layers are formed for enhancing adhesion of the photographic emulsion layer(s) to a support during photographic processing.
Photographic lightsensitive materials which tend to peel have greatly reduced commercial value.
As a method of preventing peeling of the photographic emulsion layer during photographic processing, it has been proposed in JP-A-61-69061 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") which involves controling the ratio of dextran to a binder in the photographic emulsion layer. However, this technique used alone does not completely prevent peeling of the photographic emulsion layer.